Esophago-gastro-duodenoscopy is a routine out-patient procedure which permits the direct observation, biopsy, and photography of pathological processes in the esophagus, stomach or duodenum. Duodenoscopy with cannulation and radiopaque dye injection of the common bile duct and pancreatic duct enable visualization and diagnosis of pathological processes of these organs. Therapeutic endoscopy permits (1) the control of bleeding from upper gastrointestinal sources utilizing techniques of injection of sclerosant, electrocautery, application of heater probe or laser, (2) the removal of neoplastic growths, and (3) the relief of obstructing pathological process by intubation or ablative procedures. Endoscopy requires motivation, dexterity, and experience. Patients may suffer when examinations are not properly performed.
There are three basic methods for passing the flexible endoscope. See Cotton & Williams, Practical Gastrointestinal Endoscopy, Blackwell Scientific Publications, (2d ed. 1982), p. 24-27. For all methods the patient is positioned in the left lateral decutibus position and is administered intravenous sedation and topical anesthesia to the mouth and pharynx.
(1) With mouthguard in place, the endoscopist passes the instrument tip through the mouthguard and over the tongue to the back of the mouth; the tip of the instrument is deflected in the midline over the back of the tongue and into the middle of the pharynx. The tip is advanced and the patient is asked to swallow to relax the cricopharyngeal sphincter, which lies 15-18 cm from the incisor teeth. Passage of the tip of the instrument is felt as resistance is lost. If the tip does not pass after two or three swallows, it is probably not in the midline and it should be withdrawn and repositioned.
(2) The instrument is passed through the mouthguard and over the back of the tongue into the pharynx as in method 1. The objective lens is brought to the eye of the endoscopist, and the tip of the instrument is advanced over the back of the tongue under direct vision. The patient is asked to swallow and the tip of the instrument is advanced through the sphincter under direct vision.
(3) The endoscopist passes the tip of the instrument over the tongue using the inserted fingers of his left hand to guide it into the midline of the pharynx. The patient is asked to swallow after the fingers are withdrawn and the mouthguard is placed. If swallowing is not effective, the tip of the instrument has probably fallen into the left pyriform fossa, and it may be necessary to reinsert a finger to lift the tip of the instrument back into the midline.
These methods of insertion are easier with small instruments of narrow diameter and with lateral-viewing endoscopes which have a smooth, rounded tip. Newer diagnostic and therapeutic endoscopes are of larger diameter, however, to accommodate extra channels for suction, biopsy, and laser.
In each intubation method, the most difficult and dangerous point in passing the endoscope is traversing the cricopharyngeal sphincter. The three methods above rely on the swallowing maneuver to relax this muscular sphincter and permit the endoscope to pass. There is critical dependence on the cooperation of the patient. Repeated forceful attempts to pass the endoscope through a contracted cricopharyngeal sphincter may lead to perforation of the esophagus or pharynx. The passage of the endoscope in patients who are not able to cooperate is dangerous and requires great skill on the part of the endoscopist.
Hence, prior to the present invention, a need existed for a safe technique to pass the endoscope through the cricopharyngeal sphincter with reduced risk of perforation of the esophagus or pharynx.